Outboard motor



Sem. 22, 39M. L. JI .JOHNSON OUTBOARD MOTOR Filed Ju1y24, 1929 2 Sheets'-Sheeti 4l w 0, Mul ,i Lm A Sept. 22, 1931. L J, JOHNSON 1,824,735

OUTBOARD MOTOR Filed July 24, 1929 2 Sheets-Sheet 2 llrLUerI/Y Louis J Jrohnson ffl Patented Sept. 22, 1931 UNITED STATES PATENT- OFFICE LOUIS J'. JOHNSON, OF SOUTH BEND, INDIANA, ASSIGNOR TO JOHNSON' BROTHERS ENGINEERING CORPORATION, F SOUTH BEND, INDIANA, A CORPORATION OF INDIANA OUTBOARD MOTOR Application led July 24,

This invention relates to an outboard motor and has more particularly reference to an under-water exhaust construction which is freely rotatable for reversing and for steel ing.

One of the objects of the invention is in the provision of means for discharging the engine exhaust gas below normal water level to the rear of the propeller for eliminating objectionable noise and odors.

Another object of the invention is in the provision of a tubular supporting structure for the propeller and drive shaft, which is freely rotatable about a vertical axis for steering and completely rotatable in either direction for reversing the motor when the boat to which it is attached is to be propelled rearwardly.

Still another object of this invention is in the provision of a tubular supporting structure in which there are a number of separate passages for cooling water and for the engine exhaust, all terminating below normal water level.

Another object of the invention is in the provision of an under-water exhaust construction in which there is an automatically operable pressure relief valve above normal water level for'relieving back pressure in starting, and during the operation of the motor.

Still another object of the invention is in the provision of a single supporting casing with a plurality of passages for cooling water and the engine exhaust in which the water cools the interior of the casing which would otherwise become excessively heated by the engine exhaust.

Still another object of the invention comprises the provision of separate intake passages for supplying cooling water to the engine and muiiier cooling jackets with a common discharge for the water after it has passed through the jackets.

Still another object of the invention is in the provision of a stream line under water support for the propeller having an anticavitation plate formed integral with the under water unit extending above the pro- 1929. Serial No. 380,730.

peller with the exhaust and water passages terminating below normal water level and under the anti-cavitation plate.

Still another object of the invention consists in the provision of an under water unit having a stream-lined submcrgible gear housing with an integral projecting anti-cavitation plate and with passages having outlets adjacent the front and rear sides of the propeller to induce a flow of cooling water by the action of the propeller, and an underwater exhaust opening to the rear of and below the anti-cavitation plate to receive the rearward thrust of water from the propeller thereby assisting in withdrawing and discharging the exhaust gases.

These and further objects are described in the specification and will be apparent from .the drawings which illustrate a preferred improvement of the invention.

In the drawings, F ig, 1 is a view partly in a section of an outboard motor construction made in accordance with the principles of this invention: Fig. 2 is a sectional view of the muier Fig. 3 is a sectional View showing the water pipe connections in the top of the tubular casing: Fig. 4 is a section of the tubular casing intermediate its ends: Fig. 5 is a view of the lower end of the casing unit on the line of its connection with the under water housing unit: Fig. 6 is a view of the upper end of the under water housing unit on the line of-its connection with the tubular casing and Fig. 7 is a sectional view of the under water housing unit just above the anticavitation plate.

Referring more particularly to the drawings, this invention comprises a Water propulsion device generally in the form of an inboardor outboard motor and including a power head having engine cylinders 2, a fuel tank 4, a n'ested fiy wheel magneto 6, a starter 8, a spark control lever 10, a tiller handle and mounted at one side to rotate upon a horizontal pivot 24 carried by an attachment bracket 26, so that the casing is free to rotate in the sleeve 22 about a substantially vertical axis and will swing upon the pivot 24 in a vertical plane. At the lower end of the bracket 26 are slotted guides 28 between which the casing is confined, and adjustable in the slots of these guides is a thrust plate 30 adapted to be engaged by upper and4 lower recessed lugs 32 formed on the casing 20 for preventing the motor from swinging about the horizontal pivot 24 when the motor 1s rotated approximately 180 degrees for reversing the direction of movement of a boat to which it is attached.

To the lower end of the tubular casing 20 is attached an under water housing unit 34 which provides a support for a propeller shaft 36 carrying a propeller 38 and having a bevelled gear 40, meshing with a bevelled gear 42 to the lower endv of a shaft extension 44 which is connected by a drive shaft 46 ex tending through the casing 20 with lthe crankshaft of the engine.

In the casing 20, there are partitions forming a number of passages: a large passage 48 for the engine exhaust connected laterally at its upper end with a discharge port 5() leading to the interior of the muflier 14 and with an extension 52 to the lower end of the casing member having a discharge port 54 located above normal water level and closed by an inclined plate 56 which closes the opening by gravity and is opened by pressure 1n the exhaust passage, and manually if desired-z water inlet passages 58 and 60 leading to the engine and mulier jackets: and a water discharge passage 62 which leads from the engine and muller jackets combined and discharges in a single passage, and a central'passage 63 in which the drive shaft 46 1s freely movable, preferably leaving a space between shaft and the wall of the passage 63, so that the shaft will not be heated by direct contact therewith. y

At the upper end of the casing 20 1s connected the base 18 in which is a passage 64 (Figs. 1 and 3) extending in an arc about base 18 and communicating with the upper end of passage in the casing 20. Connected into this passage 64 is a pipe 66 for conveying cooling water to the under sides of the water jackets of the cylinders 2. Pipes 68 extend from the upper sides of the cylinder and are connected by a short pipe 70 to a bore 72 in the base 18 which communicates directly with the upper end of water. discharge passage 62 in casing 20.

To circulate water through the water jacket 74 of the muier 14 a pipe 7 6 is connected into a port in the base 18 communicating directly with the upper end of water passage 58 in the casing 20, and this pipe is connected to the bottom of the muffler water jacket 74 as clearly showed in Fig. 1. Extending across the mulller is the pipe 78 connecting the top of the water jacket through the lower end oi the Inulller with a water discharge pipe 80 which leads to the common water discharge a port 72 which communicates with a water discharge passage 62 vin casing 20.

lIn the lower housing unit 34 are water inlet passages 82 and 84 terminating at the rear of the upper edge ot' the propeller blades to directly receive the water thrust rearwardly by the propeller. The upper ends of these passages are contained with the lower stream line contour of the lower water unit 34 as shown more clearly in Fig. 6, and they are connected by passages 86 and 88 respectively at the lower end of the casing 20 with up going water passages 58 and 60 respectively as shown more clearly in Fig. 5. A water discharge passage 90 communicates directly with the end of the water discharge passage 62 of the casing 20 for conveying the water downwardly through the housing and out of a port 92 adjacent the upper leading edge of propeller 38, so it will have a suction effect in withdrawing and ejecting the water. An anti-cavitation plate 94 is formed integral with the lower housing unit 34 and extends outwardly therefrom in a plane above the propeller, the water passages opening entirely below the anti-cavitation plate.

To the rear of the housing member 34 is a passage 96 which communicates with the lower end 52 of the exhaust passage 48 of the tubular casing 2O and this passage 96 extends through the anti-cavitation plate94 with a discharge opening 98 below the anticavitation plate and at the rear of the propeller where it will have the advantage of the suction produced by the propeller in throwing water rearwardly and withdrawing the exhaust from the muilier.

With this construction, it will be readily understood the operation of the motor or engine drives the propeller and the muiler receives the exhaust gases from the engine cylinders; the operation of the propeller induces a ilow of cooling water from the rear of the propeller through the separate passages in the lower unit and in the tubular casing through the jackets of the engine and the muffler and downwardly through a common discharge passage to a suction outlet in advance of the propeller; The exhaust gases from the muliler are conducted downwardly through the same tubular casing in which water passes to and from the cooling jackets and thus cools the interior of the casing, and the passage containing the driving shaft 46 and prevents undue heating of the casing 20 by means of the exhaust gases.

When the motor is at rest in starting, the lower end of the exhaust passage is under water and in order to prevent objectionable back pressure in the muler and in the eX- haust passage, a relief valve is provided above the normal water level through which the exhaust gases may escape automatically into the atmosphere, or the relief valve may be opened manually either in starting or while running.

The mounting and connection of a single tubular casing which encloses the driveshaft and provides passages for the cooling Water and the engine exhaust permits a full pivot steering about the engine drive shaft as an axis and the rotation of the entire -motor in either direction to reverse the direct movement of a boat to which it is attached.

By enclosing the driveshaft without direct contact with the tubular casing, it is less liable to become unduly heatedand will not grip the casing or expand it to interfere with its proper operation. .By making the shaft in sections,.the lower unit may be assembled in the underwater housing 34, the power head may be assembled upon the base 18 and these two units are easily casing 20 which is assembled with the supporting bracket 26. l

I claim: f y

1. An outboard motor having a jacketed combustion engine, a jacketed muHier, under-water driving means connected with the engine, and a single support casing for said means, having water inlet passages to the engine and mufiler and a common water discharge passage and an exhaust passage from the muliier terminating below the normal water level.

2. An outboard motor having a jacketed combustion engine and al jacketed muilier, a propeller having driving connection with the engine, and a single support for the propeller having separate water passages for the engine and muiier and an exhaust passage for the muiler all terminating below the normal water level.

3. A marine motor having a combustion engine and a muller therefor, each provided with a water jacket, a propeller shaft and a propeller connected to the motor, and a single support for enclosing the shaft and snpporting the propeller, the support having a number of passages terminating adjacent the propeller for inducing aflow of cooling water through the engine and-muiler jackets and having a separate passage from the mufier for the engine .exhaust discharging at l the rear of the propeller.

4. In an outboard motor having a j acketed combustion engine, ya jacketed mufler therefor, and a propeller .having driving connection with the engine,rm`eans forming an en-v closing casing for supporting the propeller and for providing a number of passages terf minating adjacent the propeller for induc ing a lowof cooling vwater through theen- 4j gine and mufller jackets, due -to the action'of the propeller and a passage for exhaust gases from the muiiler terminating at the rear of the. propeller and withdrawn by suction produced by the propeller.

5. In an outboard motor having a combustion engine and a muiler thereforand a propeller having a driving connection with the engine, means forming a support for the propeller `having an exhaust passage from the muil'ler terminating low the normal water level and a closable relief valve in the passage above normal water level for opening the passage to the atmosphere to relieve back pressure.

6. In an outboard motor, a combustion engine and a muiiier therefor, a propeller and a driving shaft therefor connected to the engine, means for supporting the propeller and enclosing the drive shaft, said means including a number of water cooling passages extending from openings adjacent the propeller to the engine and muliler, and an exhaust gas passage extending from the muler and terminating below normal Water level to the rear of the propeller, the water passages 1n the supporting means also cooling it and the exhaust gas passage therein.

7. An outboard motor having a jacketed engine and a jacketed muffler therefor, a driving shaft and a propeller connected to the motor, means for enclosing the driving shaft and supporting the propeller, said means comprising a single tubular casing having a. number of passages therethrough, 011e of the passages extending from the muflier and terminating to the rear of the propeller for conducting the exhaust gases into the propeller race and other passages extending to the engine and muiler jackets from adjacent the propeller whereby a flow of cooling water is induced through the engine and muffler jackets also cooling the tubular casing through which the hot exhaust gases pass from the muler.

8. An outboard motor having a jacketed combustion engine and a jacketed muffler therefor, depending drive shaft andy propeller connected to the motor, enclosing meansforthe shaft and forsupporting thel propeller comprising a single tubular casing. having a plurality of passages therein terminating-adjacent the propeller and below normal 'v'vaterV level for causing an induced iiowxof cooling water through the en-y gine and muiiler jackets and for `withdrawing the exhaust from the muliler and means for mounting the tubular casing to swing abouta horizontal pivot and to rotate freely about a vertical axis for ,steering and reversing.

9. In an outboardmotor the combination witha combustion engine and a mufler'therefor, of a drive shaft and a propeller in connection'withthe motor, meansl forming an ex- .n

haust passage vfrom the muiler terminating below normal waterlevel and including a closable relief valve disposed above normal water level and adapted to open automatically, due to a predeterrnined pressure in the exhaust passage and yto relieve back pressure therein in starting and running the motor.

10. In an outboard motor a jacketed combustion engine and a jacketed muiiler therefor, a drive shaft and a propeller`- in connection with the motor, supporting means for the propeller and shaft comprising a single tubular casing having a plurality of passages therein,` one of the passages enclosing the drive shaft free from Contact with the walls thereof, two passages extending from the rear of the propeller for conducting cooling- Water to the engine and muliier jackets, another passage terminating in advance of the propeller and receiving the cooling water after it has passed through the engine and muiiler jackets, and a large exhaust passage extending from the muiiier and terminating below normal water level to the rear of the propeller, the water passages being operative to cool the casing surrounding the shaft and also to cool the exhaust passage.

11. In an outboard motor having jacketed combustion engine and a jacketed mulller therefor, a drive shaft and a propeller connected to the motor, means forming passages having openings adjacent-the propeller for inducing a separate fiow of cooling water to the engine jacket and to the muiller jacket with a common discharge passage terminating in front of the propeller to receive the suction effect of the propeller.

12. An outboard motor completely rotatable about a vertical axis for reversing and steering comprising a jacketed combustion engine and a acketed muiiier therefor, a drive shaft and a propeller, means forming a single tubular support for the motor and propeller, the tubular support comprising a plurality of water passages leading to and from 'the muiiler and engine jackets and terminating adjacent the propeller, an exhaust passage leading from the mufiler through the tubular support and terminating to the rear of the propeller mounting means comprising a sleeve surrounding the tubular casing .for 1permitting a free rotation about a vertical axis, a horizontal pivot upon which a sleeve and the casing is rotatable in a vertical plane and guiding means including a thrust plate and projection extending partially around the tubular casing for engaging the thrust plate to prevent rotation of the casing in said vertical plane whenit is turned in the sleeve for driving in a reversing direction.

13. A marine motor comprising a combustion engine, a propeller and a drive shaft connecting it to the engine, a hollow casing for sup orting the propeller and .inclosing the sha having integral longitudinal partitions forming passages therein, one for the engine exhaust, and one or more for circu- .for water cooling the exhaust passageway and the interior of the casing by directly contacting with the interior partitions thereof.

15. An outboard combustion engine having a water jacket, a water jacketed mufiler therefor, and means dependent upon the operation of the engine for circulating water separately throughl the engine jacket and the muffler jacket.

16. An outboard motor comprising water jacketed cylinders,

a water jacketed muliier, and a douple water cooling syst-em for cooling the cylinders and muller.

17. A device of the class described having an internal combustion engine power plant formed with a substantially vertically depending drive shaft, a tubular housing surrounding said drive shaft, means for supporting said tubular housing for turning movement about said drive shaft as an axis, a propeller carryin casing mounted on the lower end of said tu ular housing, and means therein for operating the propeller from said drive shaft, said propeller carrying casing having an internal passage providing an underwater exhaust, and means passing through said tubular housing and connecting with the underwater exhaust and with the discharge from the gas engine, whereby the exhaust gases from the gas engine may be discharged beneath the normal water level without interfering with the proper turning of the lower unit for steerin 18. In a device of tie class described, the

combination of an internal combustion engine provided with a vertically depending drive shaft and a tubular housing surrounding the same, a propeller carrying casing rigidly connected to said tubular housing, means in the casing for driving the propeller from said drive shaft, said casing havin an anti-cavitation plate overlying the pat of travel of the propeller blades, said tubular housing and lsaid casing being constructed and arranged to form a continuous passage for conducting the cylinder exhaust gases downwardly through the `tubular casing, through the propellercarrying casing and for discharging the saine beneath the anticavitation plate and to the rear of the path of travel of the propeller blades.

19. Iii a device of the class described, the combination of an internal combustion engine provided with a substantially vertical depending drive shaft and including a tubular casing surrounding said drive shaft, a

propeller carrying casing mounted on the lower end of the tubular casing and being of stream-line contour to a point above normal waterlevel. said propeller carrying casing having a passage formed internally therein and disposed at the rear of the casing and within the stream-line thereof, said passage terminating in an open discharge mouth located below normal water level and to the rear of the path of travel of the propeller blades, said passage connnunicatmg with a passage formed in the tubular casing, the upper portion of said last mentioned passage communicating with the cylinder exhaust.

20. An outboard motor comprising a selfcontained power plant including an internal combustion engine formed with a vertically depending drive shaft and provided with a `surrounding tubular housing including a central sleeve concentrically surrounding the drive shaft, said tubular housing bein formed to provide water passages on eaci side of the concentric sleeve and an exhaust passage, means connecting the water passages with the water jacket of the engine, means connecting the exhaust passages with the cylinder exhaust, and a propeller carrying casing mounted on the lower end of said tubular casing, said propeller carrying casing being of stream-line contour and having internal passages providing water passages connecting with the water passage in the tubular housing, and an exhaust passage connecting with the exhaust passage in the tubular housing, all of the passages in the propeller carrying casing being constructed and arranged to terminate below normal water level.

2l. An outboard motor having a gas engine of the water jacketed type having a tubular casing surrounding the vertically depending drive shaft, a propeller carrying casing rigidly mounted on the lower end of said tubular casing, means for turning the casing for steering, said lower casing being of stream-line contour, said tubular casing and lower casing having registering passages for the cylinder exhaust gases and the water circulating system, said passages terminating in an outlet located below normal water level.

22. An outboard motor having a vertically depending drive shaft and a tubular housing surrounding the same, a propeller carrying casing mounted on the lower end of said tubular housing. means for turning the `same for steering, said tubular housing and lower casing being formed to provide a. continuous internal passage for discharging the cylinder exhaust gases below normal water level, and means formed in the tubular housing for discharging the exhaust gases above normal water level. f e

23. An outboard motor having a -water Jacketed engine and expansion chamber for the cylinder exhaust gases, and means for circulating water through the cylinder jacketV and expansion ackets, said means passing through the tu ular housing surrounding the vertically depending driveshaft of the outboard motor.

24. In an outboard motor, the combination of a water jackcted internal combustion engine having a crank case provided with an extension including an expansion chamber, said expansion chamber being water jacketed, means connecting the water jacket of the engine with the water jacket of the expansion chamber, said expansion chamber having an exhaust port, a tubular sleeve connected to the crank case of the engine and surrounding the vertically depending drive shaft thereof, said tubular sleeve having water passages formed therein communicating with the water jacket of the expansion chamber, said tubular sleeve having an exhaust gas passage therein communicating with the exhaust port of the expansion chamber, a propeller carrying housing carried at the lower end of the tubular sleeve and having water passages and an exhaust passage formed therein communieating with their respective passages in the tubular sleeve, said passages in the propeller 1carrlying casing opening below normal water eve 25. An outboard motor comprising in combination with the water jacketed engine having a vertically depending drive shaft, a tubular sleeve 4Connected to the crankcasingofthe engine and concentrically surrounding said drive shaft, said tubular sleeve having a central bore in which the drive shaft is housed, and said tubular sleeve having internal walls surrounding said central bore and providing passages on diametrically opposite sides thereof, and providing exhaust passages on each side of the central bore and adjacent the water passages, a propeller carrying casing mounted on the lower end of said tubular` casing and having driving means therein connected with the drive shaft of the engine, sai/d propeller carrying casing being provided with internal water conducting passages and an exhaust passage communicating respectively with the passages in the tubular housing, there being a connection from the cylinder exhaust to the exhaust passage in the tubular-housing at the upper end thereof.

. 26. In a device of the class described, thecombination of an internal combustion engine 'provided with a vertically depending drive shaft and having a tubularV housing concentrically surrounding said drive shaft and provided with an exhaust passage from the engine downwardly through the tubular housing, a propeller carrying casing of stream-like formation throughout its height, rigidly attached to the lower end of said tubular housing, means for turning said tubular housing for steering, saidy p ropellercarrying housing embodying an anti-cavitation plate disposed below the normal Water level, the upper rear portion of said propeller carrying casing being providedwith a reaward streamline extension merging intothe anti-cavitation plate and providing a internal exhaust passa e communicating with a passage .in the tu ular casing, the ower end of said 1nternal passage passing throu h theanti-cavitation plate and being provi ed with a rearwardly extending nozzle underlying the anticavitation plate, said nozzle having a substantially horizontal bottom and having latterally extending wings, said nozzle being directly in the rear of a water gathering mouth formed so as to face in a forward direction on the propeller carrying casing, said water gathering mouth communicating with an internal passage in said ropeller carrying casing and said water gat ering mouth lying adjacent to and directly in the rear of the path of travel of the propeller blades, and means connecting said water passage with a )vater passage in the tubular housing connecting with the watere jacket of the engine.

27. An outboard motor having an internal combustion engine, a vertically depending driveshaft, a tubular housing around the shaft also having an integral partition forming cooling water and exhaust passages therein, means for supporting the housing for free rotative movement about a vertical axis for steering, and an exhaust connection from the engine to the top of the housing to discharge the exhaust through the passage and from the lower end of the housing below normal water level.

28. An outboard motor having an internal combustion engine, a vertically depending driveshaft, a housing around the shaft having integrally formed exhaust gas and cooling water passages therein, a propeller operated by the shaft and an anti-cavitation plate in a'plane above the propeller, means connecting the exhaust of the engine to the upper end of the said exhaust gas passage, and means forming an outlet form the lower end of said passage below and at the rear of the said plate.

29. A water propulsion motor having an internal combustion engine, a propeller and its shaft connected to the engine by a vertical shaft, housing means rotatable about the shaft for steering and enclosing the vertical shaft and the propeller shaft and also having integral means forming a cooling lwater passage and an exhaust gas passage therein terminating in an open mouth disposed below normall water level and opening rearwardly behind the propeller, and means connecting the upper end of the exhaust gas passage-to the engine exhau'st.

30. A water propulsion motor comprising a jacketed internal combustion engine, a vertical shaft and a propeller connected thereto by the shaft, housing means including a tubular vertical casing rotatable about a vertical axis for steering and enclosing the shaft and the propeller shaft, the casing having an integral partition forming separate passages therein for cooling water and the engine exhaust, means connecting the water passages with the jacket, means connecting the exhaust passage with the en ine exhaust, and the lower ends of all of t e passages bein constructed and, arranged to terminate below normal water level.

31. An outboard motor havin a water jacketed gas engine with a vertical y depending driveshaft and a casing surrounding the f shaft and rotatable independently thereof for steering, the casing having an integral partition forming separate passages for the cooling water` andthe engine exhaust connected at the upper end to the engine and terminating at the lower end below the normal water level, and supporting means for hinging the casing about a horizontal axis and permitting rotation of the casing about a vertical axis for steering and reversing.

32. A water propulsion motor having a water jacketed engine and a water jacketed muller connected, a driveshaft and a propeller operated thereby, casing means for the driveshaft having water sages terminating adjacent to and on opposite sides of the propeller and connected to the jackets'for circulating water therethrough,

the propellerv inducing la flow of water through the passages.

33. An outboard motor having a water jacket gas engine and a connected water jacket muflier, a vertical shaft and a propeller driven thereby, an enclosing casing for the shaft and propeller, the casing having an anti-cavitation plate in a plane above the propeller and passages terminating below the plate and in front, behind and opening rearwardly from the propeller, the upper ends of the passages being connected to the muffler jacket, the engine jacket,and the mufller outlet, and being operative when the propeller is rotating in the water to circulate water through the waterjackets and to withdraw exhaust gases from the exhaust gas passage and the muler.

34. An outboard motor having a combustio`n engine, a jacketed mullier therefore, a vertical engine shaft, and an enclosing housing for the shaft having passages therein for cooling Water for the muller jacket.'

35. An outboard combustion motor having a water jacketed muffler, and means including a unitary casing rotatablel for steering having means integral with said casing forming a passage extending below water llevel for delivering cooling-water to the jacket of the muller and a passage for discharging J inlet and outlet pasexhaust gas from the muler below water level.

36. A marine combustion motor having a vertically extending drive shaft, a caslng surrounding the shaft and relatively rotatable for steering having a passage for carrying the motor exhaust therethrough, and means comprising another passage in the casing for water cooling it, said passages being formed by a partition integral with said casincf.

37. A marine combustion motor having an extending ldrive shaft, a casing surrounding the shaft having integrally formed passages for the exhaustand for the cooling water, and means for causing a flow of water through the passages for cooling.

38. An outboard motor having a combustion engine, a depending shaft and a driving propeller, a casing therefore having an anticavitation plate in a pla-ne above the propeller, and an integrally formed cooling water passage and a gas discharge passage in the casing. the engine discharging exhaust gas through the gas discharge passage below the anti-cavitation plate,

39. In an outboard motor assembly,.the combination of a support, a motor mounted thereon having a lower turnable unit of stream-line cross section,'a horizontally disposed propeller shaft mounted at the lower portion of said unit, a propeller carried thereby, a vertically disposed drive shaft connected with said propeller shaft and driven by said motor, an anti-cavitation plate extending transversely of said lower unit, means for discharging exhaust gases at a point immediately beneath and at the rearward portion of said anti-cavitation plate, and means for effecting the circulation of water to effect the cooling of said exhaust gases.

40. In an outboard motor assembly, the combination of a support, a motor mounted thereon having a lower turnable unit of stream-line construction, said unit being provided with an anti-cavitation pla-te, means for effecting the discharge of exhaust gases through and at the rear of said anti-cavitation plate, whereby gases may be effectively disposed of beneath the surface of the water, and means above the anti-cavitation plate and above the surface of the water for relieving against the development of back pressures by the exhaust gases within the motor.

41. In an outboard motor assembly, the combination of a support, a motor mounted thereon, an expansion chamber adapted to receive exhaust gases from said motor, and means independent of any motor cooling means for circulating water adjacent said expansion chamber for cooling purposes.

42. In an outboard motor assembly, the combination of a support, a motor mounted thereon. an expansion chamber associated with said motor for receiving exhaust gases therefrom, a water jacket surrounding said expansion chamber, and means independent of any motor cooling means for circulating cooling water through said water jacket.

43. In an outboard motor assembly, the combination of a support, a motor mounted thereon, an expansion chamber for receiving exhaust gases from said motor, a assageway connecting said expansion cham er with a discharge opening positioned below the normal water level, and means for circulating wateradjacent said passageway and said expansion chamber for cooling purposes.

44. In an outboard motor assembly, the combination of av support, a motormounted thereon having a lower turnable unit of stream-line cross section, an anti-cavitation plate provided on said lower turnable unit, a horizontally disposed propeller shaft mounted within said unit, a propeller carried thereby, a vertically disposed drive shaft connected with said propeller shaft and driven by said motor, a housing connecting the mo tor and lower unit for said vertical drive Shaft, and means integra-l with said unitV forming passageways in said unit for cooling water and for directing exhaust gases from the motor through the anti-cavitation plate to a discharge opening at the rea-r of said anticavitation plate in the path of water thrust rearwardly by the propeller whereby said exhaust gases may be effectively discharged beneath the surface of the water.

45. In an outboard motor assembly, the combination of a support, a motor mounted thereon having a lower turnable unit of stream-line cross section, an anti-cavitation plate provided on said lower turnable unit, a horizontally disposed propeller shaft mounted within said unit, a propeller carried thereby, a vertically disposed drive shaft connected with said propeller shaft and driven by said motor, a housing for said vertical drive shaft connecting the motor and the lower unit, an expansion chamber for receiving exhaust gases from the motor, and means integral with said unit forming passageways in the unit for cooling water and for gases from said expansion chamber to discharge through and at the rear of the anti-cavitation plate and to the rear of the propeller in the path of water therefrom, whereby said exhaust gases may be effectively discharged beneath the surface of the water.

46. In an outboard motor assembly, the combination of a support, a motor mounted thereon having a. lower turnable unit of stream-line cross section, an anti-cavitation ICO plate provided on said lower turnable unit,

a horizontally disposed propeller shaft mounted within said unit, a propeller carried thereby, a vertically disposed drive shaft connected with said propeller shaft and driven by said motor, a housing for said vertical drive shaft, a water jacketed expansion chamber for receiving exhaust gases from the m0- tor, and a passageway for directing exhaust gases from said expansion chamber' to a discharge opening positioned at a point beneath the anti-cavitation plate and to the rear ot' the propeller, whereby said exhaust gases may be ei'ectivcly discharged beneath the surface of the water, said propeller serving also as a means for circulating cooling water through the water jacket of the expansion chamber.

47. In a motor assembly for propelling a vehicle through water, the combination of a support, a motor mounted thereon having a lower turnable unit, said unit being of stream-line construction and provided with an anti-cavitation plate, and means formed integrally with said `unit for effecting the movement of cooling water therein and for the discharge of exhaust rases from said unit through the plate and below the water level.

48. In a motor assembly for propelling a vehicle through water, the combination of a support, a motor mounted thereon having a lower turnable unit provided with a streamline anti-cavitation plate and a propeller located below the plate, a stream-line water cutting section and a stream-line gearcase, and means formed integrally with said unit for etfecting the movement of cooling water therein and the discharge of exhaust gases at the rearward portion of said unit at the rear of the propeller and through the anti-cavitation plate, whereby, said gases may be disposed of beneath the surface of the water to receive the suction advantage produced by the anti-cavitation plate and the streamline passage through the water.

49. A marine combustion engine having means forming an exhaust outlet below normal water level and an exhaust outlet above water level, and automatic opening and closing means for effecting the discharge of the engine gases from the above water exhaust outlet dependent for operation upon under water exhaust resistance.

50. A marine combustion engine having means forming an exhaust outlet below normal water level and an exhaust outlet above normal water level, and automatic opening Iand closing means for discharging the exhaust gases through the above Water discharge outlet dependent upon the variations of the pressure of the under Water exhaust.

51. In an outboard motor assembly, the combination of a support, a motor mounted thereon, means connected4 with the motor for effecting the discharge of exhaust gases under water, and automatically controlled relieving means operable to cause exhaust gases to be discharged into the atmosphere when the motor is running slowly so as to relieve against the development of back pressures by the exhaust gases, and furtheroperable to effect the discharge of the exhaust In witness whereof, I have hereunder sub-.

scribed'my name.

Louis J. JoHNsoN. 

